This invention relates to bag filling machines of the type utilizing a spout having a discharge end from which particulate material is dispensed into a bag vertically suspended on the spout. Such machines conventionally utilize spout bag clamps to releasably secure the mouth of a bag onto the spout for filling. U.S. Pat. No. 4,078,358 discloses bag filling machines of such construction. Further, such bag filling machines generally incorporate bag hanging mechanism of the type disclosed in U.S. Pat. No. 4,612,965 to address the bags to the discharge end of the spout.
As disclosed in U.S. Pat. No. 5,349,996, the discharge spout of such machines may be of a clam shell type utilizing a pair of opposing, pivotal clam-jaw sections movable between closed and open positions for controllably filling a bag clamped on the spout. U.S. Pat. No. 4,432,186 discloses such spout construction on a bag filling machine. That patent also discloses the use of vertically oriented arm assemblies on the opposite sides of the machine filling spout for selective gripping and control of the gussets on the side walls of gusseted bags. Such bags present particular problems for continuously and satisfactorily holding the bag mouth on the spout during the filling of a bag, as the spout opens and closes. The aforesaid arm assemblies of U.S. Pat. No. 4,432,186 incorporate gusset clamping fingers which are disposed inside of the bag to sequentially clamp and release the inside of the gusset pleats at predetermined lateral positions as the arm assemblies are moved laterally inwardly and outwardly towards and away from the filling spout. However, the disposition of the gusset clamping fingers inside of the bag and the particular way in which those devices grip and hold the pleats of a bag during filling has not proven to be completely satisfactory. One disadvantage is that the positioning of the gusset clamping and control arm assemblies and fingers inside of a bag interferes with the flow of material into the bag.
Most recently, as disclosed in U.S. Pat. No. 5,349,996 issued to Harold R. McGregor and of common ownership herewith, a pair of clamps have been utilized on each side of the filling spout to externally grip the gussets on each side of a bag during filling. However, as shown in FIG. 5 of the aforesaid '996 patent, the gussets are clamped closed as the bag mouth is opened for filling. This has the undesirable effect of restricting the effective flow area of the bag mouth, and thereby reducing the rate at which bags can be filled.
Occasionally, the gusset clamping members intended to grip the gussets of the bag to be filled fail to properly grip the gussets. These failures may be caused by an obstruction of the path of the bag to the spout. Another cause may be that the gussets are improperly formed, e.g. opened too wide, as the bag is addressed to the spout. Improper formation of the gussets as the bag is addressed to the spout may cause the gusset gripping members to fail to properly grasp the gussets.